# CVE-2023-32735: Deserialization in SIMATIC STEP 7 Safety V16

> An attacker can execute arbitrary code by exploiting unsafe .NET BinaryFormatter deserialization in Siemens TIA Portal applications.

- **Severity:** High 7.0 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 9 Jul 2024
- **Updated:** 27 Aug 2025
- **Also known as:** GHSA-27hg-xg89-rq4f

## What is CVE-2023-32735?

CVE-2023-32735 is a high-severity unsafe deserialization vulnerability in Siemens SIMATIC STEP 7 Safety V16, published on 9 Jul 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

A vulnerability has been identified in SIMATIC STEP 7 Safety V16 (All versions < V16 Update 7), SIMATIC STEP 7 Safety V17 (All versions < V17 Update 7), SIMATIC STEP 7 Safety V18 (All versions < V18 Update 2), SIMATIC STEP 7 V16 (All versions < V16 Update 7), SIMATIC STEP 7 V17 (All versions < V17 Update 7), SIMATIC STEP 7 V18 (All versions < V18 Update 2), SIMATIC WinCC Unified V16 (All versions < V16 Update 7), SIMATIC WinCC Unified V17 (All versions < V17 Update 7), SIMATIC WinCC Unified V18 (All versions < V18 Update 2), SIMATIC WinCC V16 (All versions < V16.7), SIMATIC WinCC V17 (All versions < V17.7), SIMATIC WinCC V18 (All versions < V18 Update 2), SIMOCODE ES V16 (All versions < V16 Update 7), SIMOCODE ES V17 (All versions < V17 Update 7), SIMOCODE ES V18 (All versions < V18 Update 2), SIMOTION SCOUT TIA V5.4 SP1 (All versions), SIMOTION SCOUT TIA V5.4 SP3 (All versions), SIMOTION SCOUT TIA V5.5 SP1 (All versions), SINAMICS Startdrive V16 (All versions), SINAMICS Startdrive V17 (All versions), SINAMICS Startdrive V18 (All versions), SIRIUS Safety ES V17 (All versions < V17 Update 7), SIRIUS Safety ES V18 (All versions < V18 Update 2), SIRIUS Soft Starter ES V17 (All versions < V17 Update 7), SIRIUS Soft Starter ES V18 (All versions < V18 Update 2), Soft Starter ES V16 (All versions < V16 Update 7), TIA Portal Cloud V3.0 (All versions < V18 Update 2). Affected applications do not properly restrict the .NET BinaryFormatter when deserializing hardware configuration profiles. This could allow an attacker to cause a type confusion and execute arbitrary code within the affected application.

This is the same issue that exists for .NET BinaryFormatter https://docs.microsoft.com/en-us/visualstudio/code-quality/ca2300.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2023-32735?


## How do I fix CVE-2023-32735?

No fix has been published for CVE-2023-32735 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-32735 being exploited?

There is no known exploitation of CVE-2023-32735 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-32735 and fix it if it is affected.

What it is: CVE-2023-32735 is a high-severity unsafe deserialization vulnerability in Siemens SIMATIC STEP 7 Safety V16, published on 9 Jul 2024. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2023-32735 in the wild and no public exploit code.

Affected product: Siemens SIMATIC STEP 7 Safety V16. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-32735/ (Markdown: https://insights.sbomify.com/CVE-2023-32735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-32735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-32735
- OSV: https://osv.dev/vulnerability/CVE-2023-32735

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From sbomify Insights: https://insights.sbomify.com/CVE-2023-32735/
Summaries are generated and may contain mistakes; the official description above is the record.